yiqiuc

I've been trying to fix this annoying issue since I got the car, car is an 08 535xi. but can't seem to figure out, first was easy since the HKL module got water damage it only works closing, Bought a used one and swap that works fine for a few days, After that, it stop to open the tailgate, seems like the pump is too weak to lift the tailgate first couple inches, I have to give a little assist for the tailgate to open, Since then I check the hydraulic level, doesn't seems low, I thought maybe over time the fluid wear out, so I bought a bottle of pentofluid ehf and change it, however still act the same. during the install rear view camera and try to fix the rear window not open issue, I tear down the trims on the tailgate and it kinda start to working opening on itself again, so I think it maybe a weight issue for the pump to working too hard to lift, it works even I put all the trim back on but not the window, as soon as the rear window is shut, the tailgate stop to open with assist. Yesterday I found out as long as I park on a slope driveway with the tailgate facing down the bank, it sort of open on but I have to press the trunk button serval time. If anyone can shine some light on this will be much helpful.

kd7iwp

Have you considered that the other regular strut may be getting weak, forcing the pump to work harder than it can?

yiqiuc

I have not, tbh I completely forgot about that, but if the regular strut failed, it shouldn't have the strength to support the tailgate in the open position.

maxcbrdriver

Not necessarily. It depends on the mechanics of the strut arrangement. You've likely noticed that with the lift gate closed, the struts are positioned almost downward. I suspect it takes more force for the hydraulic cylinder to open those first few inches than it does anywhere else on it's opening arc.

neilv

I've always had that issue with mine; It seemed to only do it in the cold.

Even after I just rebuild(new seals) the pump, replaced the standard strut and greased the joints; sometimes it still stops in the first few inches. But it is way better than before

neilv

Late but I finally figured out my problem. Someone at some point replaced the HKL module and didn't code it to the car (it was set for a sedan and not a wagon) so it didn't have enough power to get started. Default code thru NCS and its like new

donpb

Thanks for the update!

yiqiuc

Good to hear the update. I still not finding what's wrong with mine. I did find out with my replacement HKL module somehow I did not change the vin to my car. but even after I changed the vin in. it's still act the same. and under coding it's showing unavailable and show the module HKL_65_2_05. I'm using protool.

neilv

Yep it looks like you have the same issue as mine. Not sure what protool is but you will have to default code the module to the car (to E61 settings). NCSexpert is the program for that.

That is as long as you got the E61 HKL(E65 should work) and not the E60 or E70 versions.